Compressor with a cylinder having improved seizure resistance and improved wear resistance, and method of manufacturing the cylinder

Abstract

A compressor has a cylinder formed of an aluminum alloy, and a moving member slidably received within the cylinder. Hard particles are dispersed in the inner peripheral surface portion of the cylinder. The hard particles are formed of a chemical compound such as a nitride and a carbide. The cylinder is manufactured by preparing a first green compact formed of a mixture of a powdery material for the aluminum alloy and the hard particles and a second green compact formed solely of the powdery material, preparing a billet having an inner layer formed of the first green compact, and an outer layer formed of said second green compact, placing the billet in a preheated state into a container and further heating same therein, and fitting a mandrel through a central bore of the billet and pressurizing the billet to extrude same through a die hole in a die.

What is claimed is: 
     
       1. In a compressor having a cylinder formed of an aluminum alloy and having an inner peripheral surface portion, and a moving member slidably received within said cylinder, the improvement wherein:   hard particles are evenly dispersed only in said inner peripheral surface portion of said cylinder and not throughout the entire extent of said cylinder;   said hard particles are formed of a chemical compound selected from the group consisting of Si 3  N 4 , TiC, and SiC; and   said cylinder is formed by subjecting a green compact of a powdery material for said aluminum alloy to hot extrusion; and   wherein said hard particles are dispersed only in an inner peripheral surface portion of said green compact which is thereafter subjected to said hot extrusion.   
     
     
       2. A compressor as claimed in claim 1, wherein said hard particles have a mean particle size of not more than approximately 10 microns. 
     
     
       3. A compressor as claimed in claim 1, wherein said aluminum alloy consists essentially of 13-17 percent by weight Si, 3-5 percent by weight Cu, 3-5 percent by weight Fe, and the balance of Al and inevitable impurities. 
     
     
       4. A compressor as claimed in claim 1, which is a vane compressor. 
     
     
       5. A compressor as claimed in claim 1, wherein said hard particles are contained in an amount of 1 to 8 percent by weight. 
     
     
       6. A compressor as claimed in claim 5, wherein said hard particles are contained in an amount of approximately 3 percent by weight.